The present invention relates to an article of footwear having one or more ground-engaging members, especially an athletic shoe having one or more selectively alterable ground-engaging members (such as spikes, cleats, etc.). More particularly, the present invention relates to ground-engaging members having a variable height.
It is generally known to provide one or more ground-engaging members protruding from the sole of a shoe, especially an athletic shoe for activities such as golf, soccer, track, baseball, and xe2x80x9cAmerican-stylexe2x80x9d football. Such ground-engaging members are variously known in the art as cleats, spikes, studs, leaves, blades, triangles, nubs, etc., and generally serve to increase traction between the shoe and the ground surface.
Furthermore, it is conventionally known to use particular types of ground-engaging members for certain types of playing surfaces. Most generally, the selection of a particular ground-engaging member requires balancing traction-increasing characteristics of the ground-engaging members versus other playing factors. For example, a player who needs to quickly or suddenly turn while running must be able to quickly pick up his or her feet from the playing surface. Otherwise, if the player xe2x80x9cplantsxe2x80x9d a foot, his or her ankle or knee may be injuriously twisted when attempting to change direction suddenly. Therefore, the ground-engaging members used in this case should not increase traction too much in order to avoid injury. On the other hand, a player whose movement involves mostly running in one direction can benefit from a relatively greater increase in traction.
Thus, for example, molded cleats made from hard rubber or a thermoplastic material are commonly used on hard/firm natural ground surfaces (e.g., hard dirt). Relatively smaller molded rubber nubs are commonly used on artificial turf and the like. Also, relatively thin spikes are conventionally used in golf and in track.
For activities taking place on soft ground (e.g., wet fields, soggy grass, or muddy ground), it is generally known to use removable ground-engaging members. This is done to enable the user to use ground-engaging members having different sizes based on the type of field being played on, and the condition of the field. Conventional removable ground-engaging members are typically engaged with a shoe sole by way of cooperating screw threads or other rotational engagement.
Changing conventional removable ground-engaging members is generally time-consuming and labor intensive, because a collection of individual ground-engaging members must be carried, and changing each ground-engaging member requires removing one ground-engaging member from a shoe in addition to mounting a new ground-engaging member. Furthermore, individual ground-engaging members may be dropped inadvertently, and, as a result, may be lost, particularly when changing ground-engaging members in a hurried manner.
Furthermore, conventional removable ground-engaging members must be adequately rotationally tightened so as to ensure good engagement between the shoe and the ground-engaging member. However, it is conventionally difficult to recognize when the ground-engaging member has been adequately tightened. Thus, the ground-engaging member may be inadvertently over-torqued in an attempt to ensure good engagement. This can damage the screw threads on the shoe and/or on the ground-engaging member, making it difficult or even impossible to subsequently disengage the ground-engaging member from the shoe when desired. On the other hand, the ground-engaging member may be inadvertently under-torqued (for example, to avoid damage caused by over-torquing). When this occurs, the ground-engaging member may not function as a stable traction device and/or may become loose and be susceptible to falling off of the shoe.
In view of the foregoing, it is desirable to provide the ground-engaging functionality of conventional ground-engaging members as discussed above, while avoiding problems associated with using individual elements that are selectively attached to a shoe sole.
The present invention is therefore generally directed to an article of footwear (such as a shoe, and especially, but not necessarily only, an athletic shoe like a cleated soccer shoe) having a selectively alterable ground-engaging member provided on a sole, and a method for altering ground-engaging characteristics of an article of footwear.
A ground-engaging member according to the present invention is preferably provided as a single unit engaged with or otherwise attached to the sole. The ground engaging member has a portion extending outwardly from the sole that is positionable at one a plurality of positions relative to the sole. For example, the ground-engaging member may include a base engaged with the sole and a tip that is selectively extendable and retractable in a telescopic manner (to a limited extent) relative to the base so as to present a selectively variable height (i.e., a distance that the ground-engaging member extends from the sole). The tip may be extended or retracted relative to the base by any suitable method, including (for example and without limitation) manually or with an appropriately shaped tool.
The ground-engaging member according to the present invention may further include a tip locking mechanism for selectively holding the tip in one or more particular positions relative to the base. Thus, for example, the tip can be telescopically moved relative to the base and selectively locked into a given position relative to the base.
In one example of the present invention, the tip may be threadedly mounted with respect to the base such that the tip can be selectively extended or retracted with respect to the base by appropriately rotating the tip relative to the base. The tip can be rotated, for example and without limitation, manually or an appropriately shaped tool, such as a tool shaped to engage a distal end portion of the tip.
In one example of the present invention, therefore, a cleated article of footwear has a plurality of cleats, each cleat including a telescoping ground-engaging portion adjustably positionable relative to the remainder of the cleat at one of a plurality of heights.
When a tip is adjusted with respect to the base according to the present invention, it is desirable to provide a detectable feedback to indicate that the tip is properly engaged in a given position. In a particular (but not exclusive) example of the present invention, the detectable feedback is an audible feedback (such as, without limitation, a snapping sound or a click sound) that a user can hear when the tip is properly located in a predetermined position relative to the base.